Add some reinforcement learning example. (#1090)

* Add some reinforcement learning example.

* Python initialization.

* Get the example to run.

* Vectorized gym envs for the atari wrappers.

* Get some simulation loop to run.

candle-examples/examples/t5/main.rs

@@ -143,7 +143,6 @@ fn main() -> Result<()> {
     let args = Args::parse();
 
     let _guard = if args.tracing {
-        println!("tracing...");
         let (chrome_layer, guard) = ChromeLayerBuilder::new().build();
         tracing_subscriber::registry().with(chrome_layer).init();
         Some(guard)